Process of making plastic material.



COMPOSITIONS,- COATING 0R PLASTIC.

No Drawing.

9am s12 orFrcE;

WILLIKM R. SEIGLE, OF NASHUA, NEW HAMPSHIRE.

PRSQESS OF MAKING PLASTIC MATERIAL9 6 9 J Specification of LettersPatent.

Application filed December 20, 1909. Serial No. 584,186.

Patented Sept. 6, 1910.

To all whom it may concern:

Be it known that I, WILLIAM R. SEIGLE, a citizen of the United States,and resident of Nashua, in the county of Hillsboro and State of NewHampshire, have invented new and useful Improvements in Processes ofMaking Plastic Material, of which the following is a specification.

My invention relates to the manufacture of miscellaneous articles out ofmaterial which is composed principally of asbestiform fiber andcementand consists m p'i'bc's sbfwliimets, boards or other masses ofsuch material are rendered amenable to plastic treatment so that curvedand irregular forms may be produced.

Sheets or plates have heretofore been produced by making a wet pulp of amixture of asbestiform fiber, cementing material and water, and thensubjecting the pulp to heavy pressure in a filter press which providesfor the expression of surplus water. The cementitious material employedhas been in some cases ma 'nesium oxid and in other cases hydraullccement such as Portland cement' the usual practice being to employequal, or approximately equal, weights of water and solid ingredients,and three parts asbestiform fiber to one part magnesium oxid, or threeparts fiber to two parts Portland cement, according to the choice ofcementitious material. Pul so compounded has, in practice, been sujected to pressure of about one ton to the square inch in order toproduce the boards required for fireproofing, electrical insulation,roofing, etc. These sheets as they come from the press are limp, butwill not bend through any small radius without breaking; theirplasticity even immediately upon withdrawal from the press is so limitedthat they are practically of no service except as flat sheets or plates,and are allowed to set in flat shape. While there are many uses to whichsuch flat sheets can be and are devoted, there are many other uses andoccasions which would be better served by such refractory sheets incurved or irregular forms. The method of compressing the pulp in pressdies of the desired-curved or lrregular sha e might be mechanicallypossible, but it is out of the question in practice; the cost ofirregularly shaped or curved dies of the necessary sizes would berohibitive even if it were feasible to handle curved masses if producedin a press.

My new method is one whereby sheets, slabs, or regular'shapes ofcement-asbestos are first prepared in the well known manner,

with preferable and advisable modifications 0 in composition andmanipulation, and then rendered plastic, so that they can be readilyshaped over forms or molds, there to set and stiffen in the desiredform. The mixture of solid ingredients which I have found to be best adated to this purpose departs from the hereto ore regularly employedproportions, but is in all essentialrespects a mixture of the same kind,possessing similar properties, as the asbestiform fiber-cementcompositions described in Nortons patents.

Nos. 84t7,293. and 929,002, dated respectively,

March 12, 1907, and July 27, 1909.

Instead of employing a mixture in which the adbestiform fiber is thepredominant solid ingredient, I have found that approximately ualuantities b Wei ht of abbestiform HBer and cement yieii the Best W resus in the process. fibrous ingredient which appears to work best, is onecomposed for the most part of cleaned hw" a e su sequen an final stepsin o r say three eighths to 35 one half an lncli on the average. Largerproportions of long asbestos fiber tend to become matted or localized,and are not desirable.

In comparison with sheets or slabs formed by filter-pressing anasbestos-cement pulp wherein the fiber is the predominant solidingredient, sheets formed by filter-pressing a pulp compounded as aboverecommended, are more plastic, possess inherently a greater capacity forbending without fracture, and lend themselves therefore to the purposesto which my new method is addressed.

Not only should the proportions of solid ingredients be modified with aneye to plasticity as the desired property, but also, the treatment ofthe materials-in the filter press requires modifications. Theapplication of heavy pressures such as heretofore employed,

of the order represented by one ton to the s uare inch compacts even n'3 i li as above r ec'ommended to such a degree of density that, thoughmeasurably superior in plasticity to similarly compressed composi- 1tions in which fiberpredominates over cement, it is not sufficientlyplastic to serve I have found, also, that the 30 uuvluv,

many of the ends which are found desirable. In order to insure thegreatest possible inherent plasticity of the mass formed by the press,the maximum pressure exerted in the pulp should be much less than thatheretofore employed, and yet great enough to give the mass suflicientconsistency and density to permit its being handled and removed from thepress without fracture. The practical minimum of pressure can hardly beprescribed definitely; pressure of 011g thousand pounds to the squareinch hamrecommend that pressure as certain to produce good results, anda safe mean between the maximum and minimum of practically possibleextremes. Thus, a mixture containing substantially equal quantities ofasbestiform fiber and cement, made into a pulp or dough with a quantityof water about equal in weight to the combined solid ingredients,compressed in a filter press to about one thousand pounds to the squareinch, produce a sheet which is inherently more plastic before finalsetting, than sheets of generally similar composition but containing alarger proportion of fiber and compressed to greater density. However,even the superior plasticity inherent in sheets composed and treated asabove described and recommended may be greatly enhanced by a furthertreatment, reliminary to the bending or molding WhlCh calls theplasticity of the sheet into requisition.

To obtain the best results, the internal structure of the sheet, and thephysical relationship of its component partlcles should be such as toyield the greatest mobility of one particle over the other, consistentlywith the integrity of the sheet as a whole. When the mass compounded asabove recommended is subjected to a pressure suflicient to insure theconcrete integrity of the sheet, but insufficient to produce the maximumdensity possible in such a sheet, the resulting product will be foundcapable of absorbing water to a degree inversely proportionate (roughlyeaking) to its density. I believe that this blbulousness of the sheetwhen taken from the press is due to the fact that although apparentlysaturated with water when in the press, the mass utilizes part of itscontained water immediately in the process of hydration, or setting,(which undoubtedly is initiated the instant that the solid ingredientsare mixed with water,) and that the mass is almost immediately ready toabsorb more water, provided its density is not such as to oppose suchabsorption.

\Vhatever may be the correct explanation of the phenomenon, the capacityof such a comparatively lightly compressed body to absorb waterimmediately after removal from the press is manifest, and it is equallymanifest that the introduction of additional WU! UHUU water to the sheetafter formation renders it decidedly more plastic than before such waterwas added. The sheet or slab, drenched and freshly saturated with watermay be bent or pressed into curved and irregular shapes over suitableforms, and presently sets in the form thus given to it. The degree ofsaturation with additional water may vary; within the limits of possibleplasticity the amount of water added or introduced to the sheet shouldbe proportionate to the degree of plasticity to be required of thesheet. For bending in easy, large curves, little water need be added,for bending or molding in curves of short radius or irregular forms, asmuch water should be added as the mass will absorb. Quick treatment andmanipulation is essential to success; not more than fifteen minu'tesshould be allowed to elapse between the removal of the sheet from thepress and its assumption of final form.

In summary, the process which I have invented is exemplified as follows:Mix equal parts by weight of asbestiform fiber and cemen'teither ,n q ga die (Portlapdi gg g entand make a Wet u P with t is mixture and aquantity of water equal in weight to the solids. Introduce the pulpimmediately to a filter press, and compress it into a sheet, reaching amaximum pressure of about one thousand pounds to the square inch. Assoon as this maximum pressure is reached, open the press, withdraw thesheet thus formed, and play water on it with a hose for about a minute,then take the wet sheet to the mold or form over which it is to bewrapped or molded, and bend or knead it into shape, leaving it on themold or form to set. By this means cylinders, cones, conoids, cylindersmerging into cones, and many other forms may be readily produced.

What I claim and desire to secure by Letters Patent is:

1. The process of manufacturing articles composed principally ofasbestiform fiber and cement which consists in making a pulp ofasbestiform fiber and cement with water, subjecting the wet pulp tofiltration pressure sufficient to insure the concrete integrity of themass while insuflicient to produce such density in the mass as willprevent it from subsequently absorbing water to a substantial degree,then causing the compressed mass to absorb water, then altering theshape of the mass and finally allowing it to set m the desired finalshape.

2. The process of manufacturing articles composed principally ofasbestiform fiber and cement which consists in making a pulp of one partfiber, one part cement, and two parts water, by weight, subjecting thewet pulp to filtration pressure suflicient to insure the concreteintegrity of the mass while insuflicient to produce such density in themass as will prevent it from subsequently absorbing water to asubstantial degree, then causing the compressed mass to absorb water,then alterin the shape of the mass and finally allowing it to set in thedesired final shape.

3. The process of manufacturing articles composed principally ofasbes'tiform fiber and cement which consists in making a pulp ofasbestiform fiber and cement with Water, subjecting the Wet pulp to afiltration-pressure of about one thousand pounds to the square inch,then causing the compressed I mass to absorb water, then alterin theshape of the mass and finally allowing 1t to set in the desired finalshape.

